U.S. patent application number 12/187727 was filed with the patent office on 2010-02-11 for cavity creator with integral cement delivery lumen.
Invention is credited to Frank J. Cinder, Jared P. Coffeen, Ryan Vanleeuwen.
Application Number | 20100036381 12/187727 |
Document ID | / |
Family ID | 41394984 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100036381 |
Kind Code |
A1 |
Vanleeuwen; Ryan ; et
al. |
February 11, 2010 |
CAVITY CREATOR WITH INTEGRAL CEMENT DELIVERY LUMEN
Abstract
A cavity creator including a tube with a lumen. A tip able to
penetrate bone extends forward from the distal end of the tube. A
blade is moveably attached to the outer tube proximal to the tip so
as to move between retracted and extended states. The tube has a
discharge port adjacent the blade. The tip is used to position the
upper tube in bone. The blade is extended to form a cavity in the
bone. Once the cavity is created filler material can be introduced
into the cavity by flowing the material through the tube lumen.
Inventors: |
Vanleeuwen; Ryan; (Portage,
MI) ; Cinder; Frank J.; (Scotts, MI) ;
Coffeen; Jared P.; (Paw Paw, MI) |
Correspondence
Address: |
INTEL. PROP./ RND;STRYKER CORPORATION
4100 EAST MILHAM AVE.
KALMAZOO
MI
49001-6197
US
|
Family ID: |
41394984 |
Appl. No.: |
12/187727 |
Filed: |
August 7, 2008 |
Current U.S.
Class: |
606/80 ;
606/93 |
Current CPC
Class: |
A61B 17/8805 20130101;
A61B 17/1671 20130101; A61B 17/1617 20130101; A61B 17/320016
20130101; A61B 2017/32004 20130101 |
Class at
Publication: |
606/80 ;
606/93 |
International
Class: |
A61B 17/56 20060101
A61B017/56; A61B 17/16 20060101 A61B017/16 |
Claims
1-3. (canceled)
4. A device for injecting cement into tissue, said device
comprising: an access cannula having a lumen that extends
longitudinally through an axis of said access cannula, opposed
proximal and distal ends, and a discharge port that opens from said
lumen adjacent said distal end of said access cannula; a fitting
adjacent said proximal end of said access cannula for receiving a
delivery device from which cement is injected into said access
cannula lumen for discharge through said discharge port; a blade
movably attached to said distal end of said access cannula so as to
move between a retracted position in which said blade is proximal
to said longitudinal axis of said access cannula and an extended
position in which said blade is spaced from said longitudinal axis
of said access cannula; a drive member that extends through said
access cannula, said drive member being movable within said access
cannula and connected to said blade for moving said blade between
said retracted and extended positions; an actuator movably mounted
to said access cannula and attached to said drive member for moving
said drive member; and a tip that extends forward from said distal
end of said access cannula, said tip configured to penetrate
tissue.
5. The device of claim 4, wherein said drive member is disposed in
said access cannula lumen.
6. The device of claim 4, wherein said drive member is positioned
in said access cannula lumen and has a section that, when said
drive member is moved to move said blade from said retracted state,
at least partially blocks said access cannula discharge port.
7. The device of claim 4, wherein said drive member further
includes at least one inclined surface that abuts a section of said
blade so as to move said blade between said extended and retracted
positions.
8. The device of claim 4, wherein said drive member is a cement
cannula that is moveably disposed in said access cannula lumen,
said cement cannula comprising: a proximal end; a distal end
positioned to engage said blade so as to move said blade between
said retracted and extended positions; a lumen that extends forward
from said proximal end; and a discharge port that opens from said
lumen adjacent said distal end; and said fitting is connected to
said cement cannula so as to establish a flow path for said cement
into said cement cannula lumen.
9. The device of claim 4, wherein said tip and said drive member
are separate components.
10. The device of claim 4, wherein said device further includes a
stylet removably positioned within said access cannula lumen, said
stylet having opposed proximal and distal ends, said stylet
dimensioned so that when said stylet is in said access cannula
lumen, said distal end of said stylet at least partially blocks
said access cannula discharge port.
11. The device of claim 10, wherein said actuator has a locking
component and said stylet has a locking component, said actuator
and said stylet locking components configured to engage when said
actuator is moved to extend said blade from said retracted state so
that, when said blade is so extended, said locking components
prevent removal of said stylet from said access cannula.
12. The device of claim 10, wherein said device further includes a
cap removably attached to a proximal end of said device and spaced
above and away from a proximal end of said drive member.
13. The device of claim 4, wherein said actuator is rotated to
longitudinally displace said drive member.
14. The device of claim 4, wherein said actuator includes an
indicator that provides an indication of the extent to which said
blade is moved from said retracted state to said extended
state.
15. A device for injecting cement into tissue, said device
comprising: an access cannula having a lumen that extends along a
longitudinal axis of said access cannula, opposed proximal and
distal ends, a discharge port that opens from said lumen adjacent
said distal end of said access cannula, and is adapted to connect
to a delivery device from which cement is injected into said access
cannula lumen for discharge through said discharge port; a blade
pivotally attached to said distal end of said access cannula so as
to move between a retracted position and an extended position; a
cement cannula disposed in said access cannula lumen and that is
movable relative to said access cannula, said cement cannula
comprised of: a proximal end; a distal end positioned to engage
said blade so as to move said blade between said retracted and
extended positions; a lumen that extends forward from said proximal
end; and a discharge port that opens from said lumen adjacent said
distal end; an actuator movably mounted to said proximal end of
said access cannula and attached to said cement cannula for moving
said cement cannula; and a tip that extends forward from said
distal end of said access cannula, said tip configured to penetrate
tissue.
16. The device of claim 15, wherein said cement cannula further
comprises a section that, when said cement cannula is moved to move
said blade from said retracted state, at least partially blocks
said access cannula discharge port.
17. The device of claim 15, wherein said access cannula further
includes a slot in which said blade is seated when in said
retracted position.
18. The device of claim 15, wherein said access cannula and said
cement cannula are positioned so that: when said cement cannula is
positioned so that said blade is in said retracted state, said
cement cannula discharge port is substantially in registration with
said access cannula discharge port; and when said cement cannula is
moved so as to move said blade from said retracted stated, said
cement cannula discharge port moves out of registration with said
access cannula discharge port.
19. The device of claim 15, wherein said tip is attached to said
cement cannula so as to extend forward from said access
cannula.
20. The device of claim 15, wherein said device further includes a
stylet removably positioned within said access cannula lumen, said
stylet having opposed proximal and distal ends, said stylet
dimensioned so that when said stylet is in said access cannula
lumen, said distal end of said stylet at least partially blocks
said access cannula discharge port.
21. The device of claim 15, wherein said actuator is rotated to
longitudinally displace said cement cannula.
22. A device for delivering bone filler material into tissue, said
device comprising: an access cannula having a proximal end and a
distal end, a longitudinal axis, and a lumen extending along said
longitudinal axis; a blade pivotally attached to said distal end of
said access cannula so as to move between a retracted position and
an extended position; a cement cannula slidably disposed in said
access cannula lumen, said access cannula adapted to be connected
to a delivery device containing said bone filler material and
longitudinally translatable within said access cannula, said cement
cannula having: a proximal end; a distal end positioned to engage
said blade so as to move said blade between said retracted and
extended positions; a lumen that extends forward from said proximal
end; and a discharge port that opens from said lumen adjacent said
distal end of said cement cannula; an actuator mounted to said
proximal end of said access cannula and attached to said cement
cannula for moving said cement cannula; and a tip attached to and
extending forward from said distal end of said access cannula to
move with said cement cannula, said tip configured to penetrate
tissue.
23. The device of claim 23, wherein said access cannula discharge
port opens from a side surface of said access cannula, said cement
cannula lumen opens from a side surface of said cement cannula, and
said access cannula discharge port and said cement cannula
discharge port are positioned so that: when said cement cannula is
positioned so that said blade is in said retracted state, said
cement cannula discharge port is substantially in registration with
said access cannula discharge port; and when said cement cannula is
moved so as to move said blade from said retracted stated, said
cement cannula discharge port moves out of registration with said
access cannula discharge port.
24. The device of claim 22, wherein said device further includes a
cap removably attached to a proximal end of said access cannula and
spaced above and away from said proximal end of said cement
cannula.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a device for
creating a cavity in bone. More particularly, the present invention
is directed to a tool for creating a cavity within a vertebra or
other bone and through which bone cement or other filler material
can be percutaneously injected into the cavity to stabilize the
bone.
BACKGROUND OF THE INVENTION
[0002] The spine, which forms the backbone of a person, consists of
a number of individual bones known as vertebrae. A vertebra can be
subjected to a compression fracture in which the normal shape of
the bone becomes compressed and distorted. Compression fractures
can occur as result of osteoporosis, a disease that results in a
loss of normal bone density, mass. Trauma to the spine or other
diseases also cause compression fractures. The fracture of one or
more vertebrae can result in extreme back pain. Other end effects
of a vertebral fracture include decreased patient height and spinal
deformity.
[0003] Vertebroplasty is a medical procedure in which bone cement
is percutaneously injected into the fractured vertebra to stabilize
the vertebra. The main goal of vertebroplasty is to reduce pain
caused by the fracture(s) by stabilizing the bone. An undesirable
side effect of vertbroplasty procedure is that the bone cement
injected into a vertebra has been known to leak. This leaked cement
can have undesirable effects on the other tissue and organs
internal to the patient. To minimize this leakage, medical
practitioners have been known to minimize as much as possible the
volume of cement that is injected in the bone. This can result in
too little cement being injected in the bone to have the desired
therapeutic effect.
[0004] An alternative procedure for treating vertebral fractures
that is related to vertebroplasty is kyphoplasty. A kyphoplasty
procedure involves placement of a balloon into a collapsed
vertebra, inflating the balloon to compress the cancellous tissue
internal to the bone in order to create a void. Once the void is
created, bone cement is injected into the void to stabilize the
fracture. Many patients have experienced appreciable relief after
undergoing a kyphoplasty procedure. However, when performing a
kyphoplasty procedure, it can be difficult to control where within
the vertebral bone the balloon inflates. This makes it difficult to
control exactly where in the bone the void is created.
Consequently, it is possible that the void will be created in space
occupied by previously healthy bone or that the void may not be
positioned at the location at which the injected cement will have
the most effect in stabilizing the fracture.
SUMMARY OF THE INVENTION
[0005] This invention relates to a new and useful cavity creator.
Specifically, this invention is related to a cavity creator that a
practitioner can insert into a vertebra or other bone and from
which a blade can be extended. The practitioner manipulates the
cavity creator to create a cavity using the blade. Once the cavity
is created, a cartridge containing bone cement or other filler
material is connected to the cavity creator. Cement/bone filler is
then injected through a lumen in the cavity creator into the
cavity.
[0006] The cavity creator comprises an outer or access cannula, an
inner or cement cannula, a blade and a knob. The blade is retracted
within the cavity creator while the cavity creator is inserted in
the vertebra or other tissue. When the knob is rotated, the cement
cannula longitudinally translates relative to the access cannula.
Translation of the cement cannula pivots the blade about a pivot
pin, extending the blade radially outward of the cannulae. Once the
blade is extended, the cavity creator is rotated to cause a like
rotation of the blade. The rotation of the blade against the bone
scrapes the bone so as to form a cavity.
[0007] The cavity creator of the instant invention does not require
the practitioner to first insert the device into the patient and
then insert the blade through the lumens or cannulas to create the
cavity. Eliminating this step simplifies the procedure and reduces
the overall amount of time it takes to perform the procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings in which:
[0009] FIG. 1 is a perspective view of the cavity creator inserted
into a patient's vertebra;
[0010] FIG. 2 is an assembly view of the cavity creator;
[0011] FIG. 3 is an exploded view of the cavity creator;
[0012] FIG. 4 is a perspective view of the distal end of the access
cannula;
[0013] FIG. 5 is a top perspective view of the handle of the cavity
creator;
[0014] FIG. 6 is a cross-sectional view of the handle shown in FIG.
5;
[0015] FIG. 7 is cross-sectional view of the cavity creator through
the handle along a plane perpendicular to the longitudinal axis of
the cavity creator;
[0016] FIG. 8 is a perspective view of the cement cannula with the
luer hub attached;
[0017] FIG. 9 is a cross-sectional view of the luer hub shown in
FIG. 8;
[0018] FIG. 10 is a longitudinal perspective view of the distal end
of the cement cannula shown in FIG. 8;
[0019] FIG. 11 is a perspective view of one embodiment of the
blade;
[0020] FIG. 12 is a perspective view of one embodiment of the pivot
pin;
[0021] FIG. 13 is a perspective assembly view of the pivot pin and
blade positioned within the cement cannula;
[0022] FIG. 14 is a cross-sectional view of the cement cannula,
blade, and pivot pin shown in FIG. 13;
[0023] FIG. 15 is a side perspective view of the distal end of the
cavity creator showing the blade seated within the tip and access
cannula;
[0024] FIG. 16 is an exploded view of the proximal end of the
cavity creator;
[0025] FIG. 17 is a cross-sectional view of the proximal end of the
cavity creator;
[0026] FIG. 18 is a perspective view of one (1) half of the knob in
which the inner portion can be viewed;
[0027] FIG. 19 is a perspective view of one (1) half of the knob in
which the outer portion can be viewed;
[0028] FIG. 20 is a perspective view of the stylet, including the
luer cap;
[0029] FIG. 21 is a cross-sectional view of the luer cap shown in
FIG. 20;
[0030] FIG. 22 is a perspective view of the handle cap;
[0031] FIG. 23 is a perspective view of the cement cannula in which
the blade is deployed;
[0032] FIG. 24 is a perspective view of the distal end of the
access cannula in which the blade is deployed;
[0033] FIG. 25 is a flowchart representing one embodiment of a
method of using the cavity creator;
[0034] FIG. 26A is a cross sectional view of a bone where the
cavity creator of this invention is in the bone forming a
cavity;
[0035] FIG. 26B is a cross sectional view of the bone after the
cavity was created;
[0036] FIG. 26C is a cross sectional view of the bone wherein a
plume of cement is discharged from the cavity creator into the
cavity;
[0037] FIG. 27 is a side view of an alternative luer hub of this
invention;
[0038] FIG. 28 is a perspective view of the underside of an
alternative stylet cap of this invention; and
[0039] FIG. 29 is a cross sectional view of how the stylet cap of
FIG. 28 engages the luer hub of FIG. 27.
DETAILED DESCRIPTION OF THE INVENTION
[0040] For the purpose of promoting an understanding of the present
invention, references are made in the text hereof to exemplary
embodiments of a cavity creation tool, only some of which are
depicted in the figures. It should nevertheless be understood that
no limitations on the scope of the invention are thereby intended.
One of ordinary skill in the art will readily appreciate that
modifications such as those involving the materials from which the
components are made, the size of the components, functional
equivalents of the elements, and the inclusion of additional
elements do not depart from the spirit and scope of the present
invention. Some of these possible modifications are discussed in
the following description. Therefore, specific details disclosed
herein are not to be interpreted as limiting, but rather as support
for the claims and as a representative basis for teaching one
skilled in the art to employ the present invention in virtually any
appropriately detailed system, structure, or manner.
[0041] As used herein, "distal" refers towards the site to which
the cavity creator is applied; "proximal" means away from the site
to which the cavity creator is applied, toward the practitioner
holding the cavity creator. The term "substantially" or
"approximately" as used herein may be applied to modify any
quantitative representation that could permissibly vary without
resulting in a change in the basic function to which it is
related.
[0042] FIG. 1 is a perspective view of cavity creator 100 of this
invention inserted into vertebra 55 of a patient 50. Cavity creator
100 comprises handle 110, knob 140, and an outer tube, access
cannula 160. Distal end 164 of access cannula 160 is inserted into
patient's 50 vertebra 55. Handle 110 and knob 140 are located at
the proximal end of access cannula 160. Once the cavity is formed
and while the cavity creator 100 remains inserted in the vertebra,
cavity creator 100 is connected to cement/filler delivery cartridge
40 via flexible tube 42. Cement or other bone filler is contained
within cartridge 40. When plunger 44 is depressed, the cement
passes through cavity creator 100 and is injected into the
cavity.
[0043] FIGS. 2 and 3 illustrate cavity creator 100 in which handle
110, knob 140, access cannula 160, and handle cap 180 can be seen.
Access cannula 160 is a substantially hollow elongated tube and
comprises proximate end 162 and an opposed distal end 164. Handle
110 is rigidly secured to proximal end 162 of access cannula 160.
Tip 170 is attached to the distal end of an inner tube, cement
cannula 200 (see FIG. 13). Tip 170 extends forward from distal end
164 of access cannula 160. Tip 170 functions as the component that
punctures the patient's skin and vertebra or other bone into which
cavity creator 100 is inserted. The cement cannula 200 has a lumen
202 that extends axially therethrough (see FIG. 13). The cement
cannula 200 is positioned substantially within the access cannula
160. Blade 210 is pivotally connected to access cannula 160 and
seated within cement cannula 200.
[0044] Stylet 230 is a substantially solid elongated rod that is
removably positioned within cement cannula 200. Handle cap 180
keeps stylet 230 within cavity creator 100 until the practitioner
intends to remove stylet 230 from cavity creator 100.
[0045] When knob 140 is rotated about Axis A, cement cannula 200 is
longitudinally displaced relative to access cannula 160. This
displacement of the cement cannula 200 pushes the pivoting blade
210 against the access cannula. This displacement of blade 210
causes the blade to rotate about pivot pin 220 to extend blade 210
outward from cavity creator 100. Cavity creator 100 is then rotated
and/or raised and lowered so that blade 210 can scrape the bone to
create the cavity. In the embodiment shown, knob 140 is made of
Nylon 6 6 plastic as manufactured by EMS-Grivory of Sumter, S.C.,
but can be made of any material commonly known and used in the art
having similar characteristics.
[0046] Also visible in FIGS. 2 and 3 is handle cap 180. Handle cap
180 extends over knob 140 and is removably secured to handle 110 to
prevent removal of stylet 230 and rotation of knob 140. Handle cap
180 also allows the practitioner to use a hammer or other device to
aid in inserting cavity creator 100 into the vertebra without
damaging the other components of cavity creator 100. Handle cap 180
is made of the same material as knob 140, but can also be made of
another material and need not be made of the same material as knob
140.
[0047] FIG. 4 illustrates distal end 164 of access cannula 160.
Center bore 158 extends end-to-end through access cannula 160. A
pair of diametrically opposed, rectangularly shaped slots 159
extend proximally rearward from distal end 164 of access cannula
160. Each slot 159 is contiguous with access cannula bore 158. A
pair of holes 153 is formed in access cannula 160 between the
slots. Holes 153 are located immediately forward of proximal end
164 of slot 159. Holes 153 are centered on a line located above the
longitudinal axis of access cannula bore 158. The line along which
the holes 153 are centered is closer to one of the two slots 159
than the other of the two slots 159. Proximally rearward of slots
159, access cannula 160 is formed to define discharge port 166.
More particularly, access cannula 160 is formed so that discharge
port 166 is longitudinally aligned with one (1) of slots 159.
Access cannula 160 is shaped so that discharge port 166 has an
elliptical shape.
[0048] FIGS. 5 and 6 illustrate handle 110. Handle 110 has a
cylindrical neck 114 that forms the distal end of handle 110. Above
neck 114, handle 110 is formed to have cylindrical core 112. Core
112 has an outer diameter greater than that of neck 114. A single
arcuately shaped shoulder 113 extends outwardly from an outer
surface of core 112. Shoulder 113 has a distal end (not identified)
that is V-shaped and directed towards the distal end of cavity
creator 100. More particularly, shoulder 113 is located on handle
110 so that the distally base of the shoulder points to access
cannula slot 159 from which blade 210 emerges. The proximal end of
core 112 has a flat shape.
[0049] Two opposed steps 108 formed integrally with core 112 extend
upwardly from the opposed sides of the proximal end of core 112.
Steps 108 have a length greater than that of the diameter of core
112 such that each step 108 extends outwardly from core 112. One
(1) tab 116 extends upwardly from each step 108. Each tab 116
generally has a cross-sectional shape of slice section through the
end of a circle. Tabs 116 are located so that each tab 116 is
slightly set back from the horizontal surface-vertical surface edge
of step 108 with which tab 116 is integral. Each tab 116 is further
formed to have around top surface 117 a lip 106 that projects
outwardly around the curved outer surface of tab 116.
[0050] Opposed arms 118 project outwardly from handle core 112.
Each arm 118 is in the form of a three-section structure
(individual sections not identified). A first section of each arm
118 projects outwardly from the distal end of core 112, adjacent
handle neck 114. A second section of an individual arm 118 extends
upwardly from the outer end of the first section. Each arm 118 has
a third section that extends inwardly from the top of the second
section. The third section of each arm 118 curves downwardly and
connects to the adjacent step 108. The first and second sections of
each arm 118 are generally planar structures. The third section of
each arm 118 is formed to so that as arm 118 approaches adjacent
step 108, the thickness of arm 118 increases.
[0051] A downwardly extending recess 120 is formed in the top
surface of the third section of each arm 118. Generally, handle 110
is shaped so that each recess 120 is defined by abutting horizontal
and vertical surfaces on arms 118 (surfaces not identified). Handle
110 is further formed to define groove 102 in each recess-defining
vertical surface of arm 118. Each groove 102 extends the width of
the vertical surface and is located a short distance above the
horizontal surface that defines the base of recess 120.
[0052] Finger 101 extends inwardly from the third section of each
arm 118. Each finger 101 extends from the surface of the associated
arm 118 that curves downwardly towards the end of the adjacent step
108. Fingers 101 project over and above the horizontal surface of
the adjacent steps 108. Each finger 101 generally is in the form of
elongated bar that extends the width of arm 118 from which each
finger 101 extends. A small groove 126 is formed in the inner face
of each finger 101, the face of finger 101 that is directed to the
opposed finger 101. Each groove 126 extends the top to bottom
length of finger 101 with which groove 126 is integral. Grooves 126
are located along the top-to-bottom longitudinal axes of fingers
101.
[0053] Two grooves 127 and 128, best seen in FIG. 7, are formed on
the vertical surface of a single one (1) of steps 108. Both grooves
127, 128 are aligned on axes parallel to the longitudinal axis of
cavity creator 100. A first of the grooves, groove 127, has a
relatively shallow depth. The second groove, groove 128, is of
deeper depth than groove 127. Both grooves 127 and 128 have a
generally circular cross sectional profile. Groove 128 has a
smaller radius of curvature than groove 127.
[0054] Handle 110 is further formed with a stop 130 (FIG. 16). Stop
130 is in the form of a rectangular and planar shaped web that
extends downward from one finger 101 to the horizontal surface of
the step 108 below the finger. More particularly, stop 130 is
located above the step 108 opposite the step 108 in which grooves
127 and 128 are formed. Stop 130 should also be understood to
project outwardly from the vertical wall (not identified) that
extends between the associated finger 101 and step 108.
[0055] Handle 110 is further formed to have a pair of opposed webs
104. Webs 104 extend outwardly from opposed surfaces of handle core
112. Each web 104 extends bottom-to-top from the opposed surfaces
of handle arm 118 first and third surfaces between which web 104 is
located. Webs 104 thus provide structural strength to handle
110.
[0056] First and second contiguous and coaxial bores 122 and 124,
extend through handle core 112 and neck 114. Bore 122 extends
downwardly from the top surface of handle core 112. (Not identified
is the small tapered counter bore that forms the actually opening
in core 112 top surface.) Bore 122 has a diameter that allows
cement cannula 200 to slidably move within the bore 122. The distal
end of bore 122 opens into bore 124. Bore 124 extends from bore 122
to the proximal end of handle neck 114. Bore 124 has a diameter
greater than that of bore 122. More particularly, bore 124 has a
diameter that allows access cannula 160 to be seated and secured in
bore 124. In some versions of the invention, access cannula 160 is
heat staked, overmolded, or adhesively secured in bore 124
[0057] It should be understood that handle steps 108 are not
equidistantly spaced apart from bore 122. The step 108 in which
grooves 127 and 128 are formed is closer to bore 122 than the
opposed step 108. Consequently, the step 108 in which the grooves
127 and 128 is longer in width, the lateral axis across the handle
110, than the opposed step 108.
[0058] FIG. 8 is a perspective view of cement cannula 200. Cement
cannula 200 is also a substantially hollow elongated shaft and
comprises distal end 204. Cement cannula 200 has an outer diameter
that allows the cement cannula to slidably move within bore 158 of
access cannula 160. Lumen 202 extends axially through cement
cannula 200. Cement cannula 200 is further formed to have at distal
end 204 a forwardly extending lip 274 (FIG. 13). Lip 274 is
generally arcuately shaped.
[0059] Cement cannula 200 is made of 304 non-hardened stainless
steel. Tip 170 is made of 17-4 pre-hard, heat treatable stainless
steel. However, one of ordinary skill in the art will recognize
that cement cannula 200 and tip 170 can be made of any sufficiently
corrosion resistant, biocompatible, rigid material and that cement
cannula 200 and tip 170 can also be made of the same material.
[0060] Luer hub 240 is secured to proximal end 206 of cement
cannula 200. As best seen in FIG. 9, luer hub 240 is formed from a
single piece of plastic that is shaped to have base 242 and head
244 coaxial with base 242. Both base 242 and head 244 are generally
cylindrical. Head 244 is located above base 242 and has an outer
diameter slightly greater than that of base 242. A first bore 247
extends upwardly from the distal end of base 242. Bore 247 is
dimensioned to receive the proximal end of cement cannula 200. Bore
247 extends approximately one quarter the way up from the bottom of
hub base 242. A second bore, bore 248, extends upwardly through hub
base 242 from bore 247 towards the top end of hub base 242. Bore
248 has a diameter less than that of bore 247. More particularly,
bore 248 has a diameter that allows stylet 230 to be slidably
advanced/retracted through bore 248. Luer hub 240 has a third bore,
bore 249, that extends upwardly from second bore 248. Bore 249 has
a diameter greater than the diameter of stylet 230. Third bore 249
is located in and extends axially through hub head 244. Bore 249
has a diameter that is greater than the diameter of bore 248. (Not
identified is the sloped surface between second bore 248 and third
bore 249. In some versions of the invention, bore 249 also has a
diameter greater than that of bore 247. While not readily visible
in the Figures, third bore 249 is also tapered inward along its
length from its proximal end to its distal end. The taper allows
luer hub 240 to connect to a luer fitting of a standard syringe or
other medical device. For example, while the distal end of tube 42
is not shown, this tube would have a fitting that allows the tube
to be connected to luer hub 240.
[0061] Threading 252 is disposed about the outer surface of hub
base 242. As discussed below, threading 252 engages complementary
threading integral with knob 140 to extend and retract cement
cannula 200. Luer hub 240 is also formed with threading 254 around
hub head 244. Threading 254 is dimensioned to engage complementary
threading associated with a luer fitting used to attach flexible
delivery tube 42 to cement cannula 200.
[0062] FIG. 10 illustrates tip 170, which is attached to distal end
204 of cement cannula 200. Tip 170 is generally cylindrically
shaped. Tip 170 is formed to have a solid, diamond shaped head 212.
The geometry of head 212 allows head 212 to puncture the soft and
hard tissue into which cavity creator 100 of this invention is
inserted. Tip 170 is shaped to form bore 214 (see FIG. 14) that
extends forward from the proximal end of tip 170. Bore 214 angles
upward into cement discharge port 266 formed along an outer
circumferential surface of tip 170. In the illustrated version of
the invention, an arcuate step 272 is formed in tip 170 around the
proximal end of tip 170. Step 272 does not extend circumferentially
around tip 170 and is not contiguous with the opening of bore 214.
As seen in FIG. 13, when cavity creator 100 of the instant
invention is assembled, cement cannula lip 274 seats in the void
space defined by step 272. This lip-in-slot arrangement ensures
that during manufacture, tip 170 assumes the proper orientation
relative to cement cannula 200. This lip-in-slot arrangement also
facilitates the torsional strength of the tip-to-cement cannula
coupling.
[0063] Referring again to FIG. 10, tip 170 is also formed to have
blade slot 216 that is located proximal to tip head 212 and forward
of discharge port 266. Blade slot 216 extends through tip 170 from
the top to the bottom. Supplemental slot 218, which is contiguous
with blade slot 216, extends rearwardly in tip 170 from blade slot
216. It should further be understood that tip 170 is formed so that
the longitudinal axis of discharge port 266 lies in the
longitudinal plane around which slots 216 and 218 are centered.
Discharge port 266 is centered along a plane that is perpendicular
to the longitudinal plane around which slots 216 and 218 are
centered. Unlike blade slot 216, supplemental slot 218 does not
extend completely through the opposed top and bottom sides of tip
170.
[0064] Tip 170 is also formed to define parallel notches 224 on
either side of the open end of supplemental slot 218. The bases of
notches 224 lie along a plane that is perpendicular to the
longitudinal plane around which slots 216 and 218 are centered. The
proximal ends of each notch 224 start along a plane located forward
of discharge port 266. Notches 224 extend forward along tip 170 to
intersect the proximal end of blade slot 216.
[0065] Parallel slots 226 extend downwardly from the base of each
notch 224. Slots 226, which start at a position approximately in
the middle of each notch 224, extend forward at approximately a
forty five degree (45.degree.) angle towards blade slot 216. As
shown, each slot 226 traverses the entire thickness of each
opposing side of tip 170.
[0066] FIG. 11 is a perspective view of blade 210. Blade 210 is
formed from material such as 17-4 pre-hard, heat treatable
stainless steel, but can also be made of any commonly known and
used material in the art having similar characteristics. Blade 210
comprises body 222 that has a generally planar shape. Body 222 has
main section 225 that has a top-to-bottom height substantially
equal to the outer diameter of access cannula 160. Inherently, this
dimension is greater than the top-to-bottom height of tip blade
slot 216. Body main section 222 has a leading edge 228 that has a
curved cross-sectional profile. Body main section 222 has trailing
edge 229 (see FIG. 14). The leading and trailing edges, 228 and 229
respectively, of blade 210 have a common radius of curvature
substantially equal to the radius of curvature of access cannula
160.
[0067] Blade body 225 has distal face 227 is the most distally
directed surface of the blade body 225. Distal face 227 extends
between the opposed sides of the blade body 225. Face 227 generally
has a rounded shape. Face 227 is further formed to have a planar
taper 231 that extends forward from the distal end of trailing edge
229. Taper 231 provides clearance for blade 210 so the blade can
rotate in and out of tip blade slot 216.
[0068] Blade body 225 is further formed to have a tail 270 that
extends rearward and is coplanar with main section 225. Tail 270
has a top to bottom height less than that of body main section 225.
More particularly, blade 210 is shaped so that when blade main
section 225 seats in blade slot 216, blade tail 270 seats in
supplemental slot 218 and tail 270 extends into the void space
subtended by tip notches 224. The upper edge of blade tail 270 is
located below leading edge 228 of main section 225. Blade tail 270
further comprises tapered corners 273 located forward of the
proximal end of blade tail 270.
[0069] Throughhole 276 extends side-to-side through blade tail 270
immediately below the top edge of tail 270. Opposed posts 278
extend outwardly from the opposed sides of blade tail 270. Posts
278, which are cylindrical, are located forward and below
throughhole 276. Posts 278 fit within slots 226.
[0070] FIG. 12 is a perspective view of pivot pin 220. Pivot pin
220 is substantially cylindrical and comprises two (2) opposing
outer surfaces 238. Outer surfaces 238 are slightly arcuate to
correspond to the rounded outer surface of access cannula 160.
While not apparent in the drawings, pivot pin 220 is slightly
tapered along its length, with the diameter of the of one end being
slightly larger than the diameter of the opposed end.
[0071] As seen by reference to FIGS. 13, 14 and 15, when cavity
creator 100 is assembled, pivot pin 220 extends through blade
throughhole 276. Blade 210 is positioned in tip 170 so that body
main section 225 of blade 210 seats in tip blade slot 216 and body
tail 270 seats in supplemental slot 218. Owing to the relative
dimensions of tip 170 and blade 210, the opposed side edges of
blade 210 project beyond the outer circumferential surface of tip
270. As a consequence of the seating of blade 210 in tip 170, each
post 278 seats in an adjacent tip slot 226. The opposed ends of
pivot pin 220 extend through and over and beyond notches 224. Owing
to the shaping of access cannula 160 and pivot pin 220, the
arcuately shaped opposed outer surfaces 238 of pivot pin 220 are
flush with the outer circumferential surface of access cannula
160.
[0072] Upon assembly of cavity creator 100, distal end 164 of
cement cannula 200 and the portion of tip 170 proximal to head 212
are seated within access cannula bore 158. Tip blade slot 216 is in
registration with the opposed access cannula slots 159. The opposed
ends of pivot pin 220 are fixedly secured via press fit in the
opposed access cannula holes 153. One access cannula hole 153 is
slightly larger than the other such that each end of pivot pin 220
can be press fit within each access cannula hole 153. Specifically,
upon assembly, the end of pivot pin 220 having a smaller diameter
is slid through access cannula hole 153 having a larger diameter
and into access cannula hole 153 having a smaller diameter. The
result is that pivot pin 220 can be slid along the width of access
cannula 160, but each end press fit within the corresponding access
cannula hole 153.
[0073] Lumen 202 leads into tip bore 214 at approximately a
30.degree. angle relative to Axis A to form discharge port 266.
[0074] Tip 170 further includes projection 282, which is below tail
270 of blade 210 and extends forward to form the bottom surface of
tip 170. Projection 282 is therefore arcuately shaped. Projection
282 also forms the bottom of supplemental slot 218, but does not
extend to head 212. Because it does not extend along the entire
length of tip 170, projection 282 allows blade slot 216 to traverse
tip 170 from top to bottom.
[0075] Owing to the relative dimensioning of access cannula 160 and
blade 210, blade 210 is substantially flush with access cannula 160
so as not to catch on tissue when cavity creator 100 is inserted
into the patient. Also visible in FIG. 15 is tapered surface 284
around the distal end of tip 170. Tapered surface 284 is angled
inward between the diameter of access cannula 160 and approximately
the outer diameter of head 212. Tapered surface 284 further reduces
the likelihood of access cannula 160 catching tissue when cavity
creator 100 is inserted in the patient.
[0076] It should be appreciated that a feature of this invention is
that blade 210 extends forward from tip 170 as close as possible to
the distal end and that cement discharge port 266 is open as close
as possible to the distal end of the tip 170. To facilitate these
design criteria, blade is formed with taper 231. Taper 231 has a
slope that makes it possible to minimize the distance between the
distal end of blade 210 and the adjacent inner wall of tip 170 that
defines the distal end of blade slot 216. Similarly, the proximally
directed corners 269 of blade tail 270 are tapered (tapers not
identified). These tapers reduce the spacing between the blade tail
270 and the distally directed internal surface of the tip that
defines the proximal end of slot 216. These features make it
possible to construct the tip so that in many versions of the
invention, the maximum distance the distal end of the tip head 214
and the proximal ends of slots 224 is no greater than 0.200 inches.
In more preferred versions of the invention, this maximum
separation between these two features of tip 170 is no more than
0.150 inches. In turn, this makes it possible to fabricate tip 170
so that the cement discharge port 266 opens within 0.250 inches of
the distal end of the tip and, in more preferred versions of the
invention, within 0.200 inches of this end. Ideally bore 214 should
be relatively wide to facilitate the discharge of cement with as
free as flow as possible. In some versions of the invention bore
214 should have a diameter of at least 0.050 inches.
[0077] FIGS. 16 and 17 are exploded and cross-sectional views,
respectively, of the proximal end of cavity creator 100. Knob 140,
best seen in FIGS. 18 and 19, is shaped to have a body 142 and two
(2) downwardly extending rings 146, 148. The first ring 146 extends
downward from the outer portion of the bottom surface of body 142.
The second ring 148 extends downward from the center of the bottom
surface of body 142 and forms bore 150. First ring 146 is outward
of second ring 148, which are separated by gap 152.
[0078] Second ring 148 comprises two (2) sections (not identified).
The first section is proximate to knob body 142. The second section
is below the first section and has a smaller diameter than the
first section. The two (2) sections define a step 143 therebetween.
The second section, it should be understood, has a diameter
slightly less than the distance between handle steps 108.
[0079] Bore 150 of second ring 148 is formed to have threading 154
on its inner surface. Threading 252 on the outer surface of base
242 of luer hub 240 engages complementary threading 154. Luer hub
240 therefore converts the rotation of knob 140 to longitudinal
displacement of cement cannula 200 to extend and retract blade
210.
[0080] First ring 146 comprises inwardly extending lip 256. When
cavity creator 100 is assembled, tabs 116 of handle 110 (see FIGS.
5 and 6) extend upward into gap 152. Lip 256 is disposed below the
outwardly projecting lips 106 integral with handle tabs 116. The
lip-under-lip arrangement allows knob 140 to rotate, but does not
allow it to be upwardly removed from handle 110.
[0081] As can be seen in FIG. 16, knob 140 comprises two (2)
matable halves. Referring now to FIG. 18, in which the male half of
knob 140 is shown, the male half includes six (6) mating members
156. The female half (not shown) includes six (6) corresponding
receiving members for engaging mating members 156. Mating members
156 and the corresponding receiving members are press fit together.
It should be understood that the two (2) halves of knob 140 can
alternately be secured to one another by a greater or lesser number
of mating members 156 and receiving members, by heat, an adhesive,
screws, or any combination thereof.
[0082] Referring to FIGS. 18 and 19, one half of circular opening
138 formed in the top of knob body 142 can be seen. Opening 138 is
dimensioned to receive luer cap 260. Knob body 142 is further
shaped to have notch 144 that extends radially outwardly from
opening 138. Notch 144 is sized to allow luer cap tab 255 (see FIG.
21) to pass therethrough when properly aligned in order to remove
stylet 230.
[0083] Also visible in FIGS. 18 and 19 is one half of slot 134.
Each half of knob 140 includes one half of slot 134 such that when
mated, the halves form slot 134. Slot 134 is formed as part of knob
top surface 136 and that part of top surface 136 forming slot 134
has a thinner thickness as compared to the remaining portion of
knob top surface 136. Slot 134 extends along the opposing inner
facing mating surfaces of each half of knob 140 and extends from
the outer edge of opening 138 to the outermost edge of knob 140.
Slot is further oriented substantially perpendicular to notch 144.
When assembled and handle cap 180 is positioned over handle 110,
slot 134 receives rib 188 on the under surface of handle cap arms
186 (see FIG. 22). With ribs 188 positioned within slot 134, knob
140 cannot be rotated. Handle cap 180 therefore prevents rotation
of knob 140.
[0084] With reference to FIG. 19, positioned on outer surface 145
of knob 140 are four (4) outwardly extending detents 288. Detents
288 are oriented along axes parallel to the longitudinally axis of
cavity creator 100. In the drawings, not all four (4) detents 288
are visible. Specifically, in the embodiment shown, a first detent
288 (on the left of body 142) is positioned on outer surface 145 of
knob 140. The other half of knob 140 has a similarly located detent
288. Detent 288 (located on the right of body 142) is only a half
of a detent. The other half of knob 140 has a corresponding half
detent 288 that, when the two (2) halves are mated, form a full
detent 288. Similarly, each half further includes a second half
detent 288 on the opposite mating side (not visible). The result is
four (4) full detents 288. Detents 288 are all spaced apart from
one another at approximately ninety degree (90.degree.)
increments.
[0085] Ribs 286 are also visible on the outside of body 142.
Because the practitioner may be wearing gloves and/or have fluids
on their hand, ribs 286 allow the practitioner to better grip knob
140. Knob 140 can have any number of ribs 286, and it is not
intended that ribs 286 be limited to any width, depth, spacing
between, or orientation. As an alternate gripping mechanism, knob
140 can further include studs, textured portion(s), an elastomeric
material positioned on any portion or entirely around knob 140, or
any combination thereof.
[0086] Also visible in FIGS. 18 and 19 are slot 290 and corners
292, 293. Slot 290 is formed in first ring 146 and extends
circumferentially around an outer section of ring 146. Each half
that forms knob 140 is formed with slot 290. Slots 290 are present
for manufacturing reasons and are otherwise not relevant to this
invention. Corners 292, 293 are rounded surface where each vertical
surface meets the horizontal surface of rings 146, 148. The rounded
surfaces are also not integral to the invention.
[0087] Knob second ring 148 is further formed to have a single
outwardly extending rib 172 seen best in FIG. 19. Rib 172 is
dimensioned to fit in handle grooves 127 and 128. More
particularly, rib 172 has a radius of curvature that is less than
the radius of curvature of groove 127. Knob 140 is further formed
to have a single tab 235, seen in cross section in FIG. 17. Tab 235
extends radially outwardly from the distal end of knob first ring
146.
[0088] FIG. 20 shows stylet 230, including luer cap 260. Stylet 230
is a substantially solid rod and comprises distal end 234 and
proximal end 236. Stylet 230 has an outer diameter that allows
stylet 230 to slip fit within cement cannula lumen 202. Luer cap
260 is fitted over and secured to proximal end 236 of stylet 230.
Plug 232 is secured to distal end 234 of stylet 230 and made of a
flexible material. Stylet 230 and plug 232 are collectively shaped
so that plug 232 extends forward of cement cannula 200.
[0089] Stylet 230 is shaped so that the distal end of the stylet
does not extend into tip 170. When stylet 230 is positioned within
cement cannula 200, at least a portion of stylet plug 232 extends
through tip bore 214 towards the access cannula discharge port 166.
Stylet plug 232 does not extend out of the access cannula discharge
port 166. This design feature substantially eliminates the
possibility that, when the cavity creator 100 is inserted in the
patient, tissue will catch in discharge ports 166 and 266. Stylet
230 is held in place by the frictional engagement between stylet
plug 232 and bore 214 to prevent rotation of stylet 230. Because
stylet plug 232 is made of a flexible material, it can be slid
along lumen 202 of cement cannula 200 and bend off axis from the
stylet 230 to extend into tip bore 214.
[0090] Stylet plug 232 is made of an elastomeric material such as
that manufactured under the trademark Santoprene.RTM. by Advanced
Elastomer Systems of Akron, Ohio but can be made of any other
natural or man-made material having similar flexibility,
durability, and biocompatibility characteristics, including
silicone. Stylet 230 is made of 316 stainless steel, but can
alternately be made of another sufficiently corrosion-resistant,
biocompatible, and strong material, including but not limited to
420 stainless steel, 304 stainless steel, and 17-4 pre-hardened
stainless steel. Luer cap 260 is made of the same material as
handle 110, but can also be made of any material commonly known and
used in the art having similar characteristics.
[0091] Luer cap 260, as seen by reference to FIGS. 20 and 21, is
generally cylindrical and comprises body 262, outer skirt 267,
inner skirt 268, recess 258 between skirts 267, 268, tab 255, and
luer boss 280. Body 262 is substantially cylindrical. Luer boss 280
is integrally formed with and positioned on the proximal end of
luer body 262. Boss 280 is also substantially cylindrical in shape
and extends outward from body 262. Luer boss 280 also extends
upward beyond the top surface of knob 140 when stylet 230 is
positioned within cavity creator 100. Luer boss 280 allows the
practitioner to grasp luer cap 260.
[0092] At the distal end of luer body 262 are outer skirt 267 and
inner skirt 268. Outer skirt 267 is positioned outward of luer body
262 to approximately the same diameter as luer boss 280 and extends
downward from body 262. Inner skirt 268 extends downward from body
262 below outer skirt 267. Inner skirt 268 is further formed to
have a tapered outer diameter that increases from the distal end of
skirt 268.
[0093] Inner skirt 268, body 262, and a portion of boss 280 also
form a generally cylindrical bore 264. Bore 264 is sized to receive
proximal end 236 of stylet 230. Luer cap 260 is overmolded onto
stylet 230.
[0094] Tab 255 extends radially outward from outer skirt 267 and
prevents stylet 230 from being unintentionally removed from lumen
202. Specifically, in order to remove stylet 230, tab 255 must be
aligned with notch 144 (see FIG. 18) in top surface 136 of knob
140.
[0095] FIG. 22 illustrates cap 180. Cap 180 can be made out of the
same material from which handle 110 is formed. Cap 180 is formed as
a single piece component shaped to have head 182 in form of a flat
surfaced dome. As seen best in FIG. 17, the undersurface of head
182 is shaped to have cavity 184. Cavity 184 is dimensioned to
receive the top of luer cap 260. Two arms 186 extend radially
outwardly from the opposed sides of head 182. Each arm 186 is
generally in the form of a bar that curves downwardly as arm 186
extends away from head 182. Extending downwardly from the
undersurface of each arm 186 is rib 188. Ribs 188 have a
side-to-side width less than arms 186 from which ribs 188 extend.
Ribs 188 mate with slot 134 on top surface 136 of knob 140 to
prevent rotation of knob 140 until knob cap 180 is removed.
[0096] Fingers 190 extend downwardly from the undersurface of each
arm 186. Fingers 190 are located inwardly of the outer ends of each
arm 186. Each rib 188 abuts the end of the associated finger 190.
Fingers 190 are formed to have a T-shaped cross sectional profile
such that each finger 190 has flange 192. Cap 180 is further shaped
so that finger flanges 192 are directed inwardly, towards each
other. Flanges 192 provide structural support for when cavity
creator 100 is hit with an impact device. Knuckles 195 extend
outwardly from each finger flange 192. Knuckles 195 are thus
directed inward toward each other. Each knuckle 195 is in the shape
of a triangle that has a notch that extends inwardly from the apex
(notch not identified).
[0097] Cap 180 is further formed so that fingers 190 have widths
that allow fingers 190 to seat in the opposed handle recesses 120.
When cap 180 is so positioned, knuckles 195 seat in grooves 102
formed in handle 110. The seating of cap knuckles 195 in handle
grooves 102 serves to releasably hold cap 180 to handle 110.
[0098] Also, handle cap 180 is shaped so that when handle cap 180
is seated over the rest of cavity creator 100, as seen in FIG. 17,
there is first gap 174 between the top of luer cap 260 and the
adjacent undersurface of cap head 182. There is also a smaller and
outwardly directed second gap 176 between ribs 188 below each arm
186 and top surface 136 of knob 140.
[0099] In use, cavity creator 100 can be used by performing the
following steps. It should be noted that not every step need be
included in every procedure involving cavity creator 100 and that
additional and/or equivalent steps can be included without
departing from the spirit and scope of the invention.
[0100] FIG. 25 is a flowchart representing one (1) method 300 of
using cavity creator 100 of the instant invention. In using cavity
creator 100, the following steps can be performed: inserting the
cavity creator 310, extending the blade 320, creating a cavity 330,
retracting the blade 335, withdrawing the stylet 340, connecting
the cavity creator to a canister 350, injecting cement or another
material into the cavity through the cavity creator 360, and
removing the cavity creator 370.
[0101] Upon assembly of cavity creator 100, a pair of opposed knob
detents 288 are seated in handle finger grooves 126. Knob rib 172
is, at this time, seated in handle groove 127.
[0102] Step 310 comprises inserting cavity creator 100 into
vertebra 55 or other bone tissue, whether additional tissue must be
traversed (for example, through skin over vertebra 55) or vertebra
55 or other bone is exposed. Sometimes, prior to the actual
insertion of cavity creator 100, a small incision is made to form
an opening in the skin at which the cavity creator 100 is to be
inserted.
[0103] The actual insertion is typically done by hand, but a hammer
or other impact device can also be used to insert cavity creator
100. During this process the head of the hammer is brought down
against cap head 182. The force of this impact is transferred
through cap arms 186 and fingers 190 to handle 110. From handle
110, the force is transmitted through access cannula 160 to tip
170. It should further be appreciated that because cap head 182 is
spaced above stylet cap 260 this impact force is not transferred to
stylet 230. Thus, the driving of cannulas 160 and 200 into the bone
does not result in the simultaneous further driving of stylet 230
out of access cannula discharge port 166. If a very large amount of
impact energy is applied to cap 180, cap arms 186 will flex.
Typically, the degree of arm flexure is such that the arms 186 do
not contact and therefore do not transfer energy to the underlying
surfaces of knob 140. This flexure thus substantially eliminates
the likelihood that the application of energy to cap 180 will
result in structural failure of cap 180 or the underlying knob
140.
[0104] During cavity creator insertion, it should be appreciated
that blade 210 is in the retracted state, the longitudinal axis of
the blade is at least parallel to if not aligned with the
longitudinal axis of access cannula 160. Also, stylet tip 232 is
disposed in tip bore 214. The presence of tip 232 in bore 214
during the insertion process reduces the likelihood that, during
the insertion process, tissue will catch in the access cannula
discharge port 166 or tip bore 214.
[0105] To extend the blade, step 320, handle cap 180 is first
removed from the rest of cavity creator 100. The removal of cap 180
moves cap ribs 188 away from knob step 134. This allows knob 140 to
be rotated. Prior to the actual extension of blade 210, the
practitioner may rotate cavity creator 100 so blade 210 will extend
into the specific section of bone in which the cavity is to be
formed. As a consequence of the extension of the blade 210 the
longitudinal axis of the blade becomes angled relative to the
longitudinal axis of the access cannula 160. Specifically, cavity
creator 100 is rotated until the base of handle shoulder 113 points
to the section of the bone into which the practitioner wants blade
210 to extend.
[0106] Blade 210 is extended by rotating knob 140. Upon initial
rotation of knob 140, knob rib 172 rotates out of handle groove
127. Handle 110 is dimensioned such that during this displacement
of knob 140, rib 172 does not abut the surface of handle 110 that
defines groove 127. Accordingly, this displacement of rib 172 does
not provide tactile feedback to the practitioner that knob 140 is
being rotated. The initial rotation of handle 140 also
simultaneously forces knob detents 288 out of handle grooves 126.
The abutment of detents 288 against the groove-defining surfaces of
handle 110 does provide a tactile feedback of knob 140
rotation.
[0107] When knob 140 is turned, the inner or cement cannula 200
longitudinally translates relative to the outer or access cannula
160. Pivot pin 220 is fixed relative to access cannula 160, and
blade 210 is positioned within cannulas 160, 200. When cement
cannula 200 and tip 170 are longitudinally translated forward, the
rear surfaces of tip 170 that define slots 226 are pushed against
posts 278 on blade 210, as seen in FIG. 23. This action pushes
blade 210 outwardly so that blade 210 rotates around pivot pin 220
and extends out of one of the access cannula slots 159 as seen in
FIG. 24.
[0108] The rotation of knob 140 also rotates knob notch 144 so that
the notch moves out of registration with stylet cap tab 255. This
new orientation of knob 140 relative to luer cap tab 255 places
knob 140 in the position in which knob 140 blocks removal of luer
cap tab 255 and therefore the whole of stylet 230, from the rest of
cavity creator 100. During this process, since the stylet plug 232
is disposed in tip bore 214, the plug 232 is in an off axis
position to stylet 230 itself. This off axis position of stylet
plug 232 inhibits the manual rotation of stylet 230 that could
place luer cap tab 255 in registration with knob notch 144. Thus,
collectively, the inhibiting of the rotation of stylet 230 and the
reorientation of knob 140 mean that when knob 140 is rotated to
extend blade 210, stylet 230 is blocked from removal from the rest
of the assembly.
[0109] By selectively rotating knob 140, the practitioner regulates
the extent to which blade 210 projects away from access cannula
160. Detents 288 provide an indication of the extent to which knob
140 is rotated from the initial state so as to provide an
indication of the degree of blade extension. Specifically, once
knob 140 is rotated 90.degree. from the initial state, a second
pair of opposed detents 288 seat in handle grooves 126 to provide
an indication of the quarter-turn rotation of knob 140. This means
that the blade 210 is extended approximately one-quarter from its
retracted state. The rotation of knob 140 180.degree. results in
the opposed pair of detents 288 that were initially seated in the
handle grooves 126 reseat in the grooves. However, each detent 288
seats in a groove 126 opposite the groove 126 in which the detent
288 was initially seated. This seating of detents 288 provides
tactile feedback that knob 140 has undergone a half turn of
rotation. This should, in turn, be understood to mean that the
blade 210 is approximately half way between the fully retracted and
fully extended states. When knob 140 is rotated 270.degree., the
second pair of opposed detents 288 again seat in handle grooves
126. The movement of detents 288 in and out of grooves 126 provides
the indication that knob 140 has undergone more that a
three-quarters turn rotation. It should therefore be understood
that the blade 210 should be considered about three-quarters fully
extended.
[0110] In the described version of the invention, knob 140 is not
rotated a full 360.degree.. Instead, the knob is able to rotate
between typically between 330 and 350.degree.. In some versions of
the invention, the knob is able to rotate between 340 and
345.degree.. When the knob 140 is fully rotated, the blade 210
fully extended, knob rib 172 seats in handle groove 128. The
seating of rib 172 in groove 128 provides the tactile feedback that
the knob is fully rotated. Should one try to force further rotation
of knob 140, knob tab 235 abuts handle stop 130 to prevent such
movement.
[0111] Once blade 210 is extended, the cavity is created in the
bone, step 330. This step is performed by the practitioner rotating
cavity creator 110. This rotation causes blade 210 to move against
and scrape the porous cancellous tissue 306 that forms the center
of the bone 302 as seen in FIG. 26A. In the Figures, the dense
cortical tissue 304 that forms the outer shell of bone 302 is
represented by dense stippling; the inner porous cancellous tissue
306 is represented by sparse stippling. As seen by FIG. 26B, the
grinding of the cancellous tissue 306 forms a cavity 308 in the
bone 302 where this tissue was previously located. Again, the
practitioner is able to selectively control where in the bone 302
the cavity 308 is created by regulating the arc through which blade
210 is rotated. The practitioner monitors blade position by
monitoring the location of the distally directed base of the handle
shoulder 113. During this process, cavity creator 100 can be
displaced longitudinally. This allows the practitioner to set the
length of the cavity 308. Likewise, it should be appreciated that
the practitioner may chose to first partially extend the blade and
create a small cavity. Once this small cavity is created the
practitioner may then more fully extend the blade 210 to create a
larger cavity.
[0112] Cavity creator 100 can be completely rotated to form a
360.degree. cavity around cavity creator 100 or can be rotated to
an extent less than complete rotation to create a cavity only
around a portion of cavity creator 100. Cavity creator 100 can,
while being rotated, also be moved longitudinally to create a
cavity that is longer than the length of blade 210.
[0113] During the cavity creation process, stylet plug 232 is
disposed is disposed in tip bore 214. Plug 232 prevents tip bore
214 and cement cannula lumen 202 from clogging, which could inhibit
the subsequent delivery of cement. Also, while blade 210 is
extended, owing to the forward longitudinal displacement of the
cement cannula 200 and tip 170 relative to the access cannula 160,
tip discharge port 266 moves out of registration with the access
cannula discharge port 166. More particularly, the section of the
tip 170 proximal to discharge port 266 moves under the access
cannula discharge port 166. This further blocks the flow of
material into tip bore 214 and cement lumen 202.
[0114] Once the cavity is created, blade 210 is retracted, step
335, by reversely rotating knob 140. The rotation of knob 140
causes cement cannula 200 to retract proximally rearward. This
results in blade pins 278 being pressed against the surfaces of tip
170 that define the distal ends of slots 226. The pressing of the
blade pins 278 against these surfaces rotates blade 210 about pivot
pin 220 to the retracted position. As a consequence of this
rotation of knob 140, knob notch 144 is rotated back into alignment
with luer cap tab 255. Thus, at this time stylet 230 can be removed
form cavity creator 100, step 340.
[0115] It should further be appreciated that the retraction of the
cement cannula 200 proximally rearward places the tip discharge
port 266 back into registration with the access cannula discharge
port 166.
[0116] Step 350 comprises connecting cavity creator 100 to
cartridge 40. Bone cement or other filler material to be injected
into the cavity is contained in cartridge 40. Cartridge 40 is
mechanically connected to cavity creator 100 by flexible tubing 42
or other appropriate means. As shown herein, flexible tubing 42 is
connected to cavity creator 100 by a threaded fitting (not shown)
on flexible tubing 42 that mates with threading 254 on luer hub
240.
[0117] Step 360 comprises injecting the bone cement or other filler
material into to the cavity. The material is ejected from cartridge
40 using plunger 44, but can be ejected using any other mechanism
or device. The ejected material passes through flexible tubing 42,
through lumen 202, cement cannula discharge ports 266 and access
cannula discharge port 166 into the cavity 308 as seen in FIG. 26C.
In FIG. 26C a plume of cement 309 is seen discharged from the
access cannula port 166 into the cavity 308. The mass of cement
fixates fractures present in the bone. The injection of other
filler material into the bone cavity provides the same or other
therapeutic benefit.
[0118] The present invention is not limited to the particular
material being injected or the type of bone into which the material
is being injected. Such a procedure allows the practitioner to
control the time at which the material being injected (that is,
early in the curing process in which the material is less viscous
or later in the curing process in which the material is more
viscous), the volume of the material being injected, as well as the
pressure at which the material is injected.
[0119] Step 370 comprises removing cavity creator 100 from the
patient. That is, once the material has been injected into the
cavity, cavity creator 100 is extracted from the bone and any other
tissue that cavity creator 100 passed through to get to the
bone.
[0120] It should be appreciated that a feature of this invention
therefore is that it provides a single device for: penetrating the
bone; forming the cavity in the bone; and functioning as the
delivery conduit through which the filler material can then be
introduced into the cavity. The need to use plural instruments to
perform these steps is therefore eliminated. Eliminating the need
to position plural instruments in the bone both minimizes the
complexity of the procedure and the overall amount of time it takes
to perform the procedure.
[0121] With respect to the method shown and described herein, it
should be understood that the steps need not be performed in any
particular order. For example, step 350 of connecting cavity
creator 100 to cartridge 40 can be performed between or during
other steps of method 300.
[0122] While cavity creator 100 and method of using same has been
shown and described primarily with respect to one (1) specific
version, from the above description it should be clear that the
same is not limited thereto, but is susceptible to numerous changes
and modifications as known to a person of ordinary skill in the
art. There is no requirement that all versions of the invention
include each of the above-described features. For example, cavity
creator 100 need not include handle cap 180. As a further example,
knob 140 need not have ribs 286 or another means for helping the
practitioner grasp cavity creator 100. In addition, threading 254
on luer hub head 244 is only one way by which delivery tube 42 can
be attached to cement cannula 200. For example, in one alternate
version, delivery tube 42 frictionally engages luer hub 240 such
that threading 254 is unnecessary. In some versions of the
invention, the pivot pin 220 may be welded to the access cannula
160.
[0123] Likewise, it may not be necessary in some versions of the
invention to provide the stylet 230 with a flexible plug that
extends towards the tip discharge port 266.
[0124] In versions of the invention in which the stylet is not
provided with a plug or in other versions of the invention,
alternative means may be provided to prevent removal of the stylet
230 when the blade 210 is in the extended state. For example in one
alternative version of the invention, an alternative luer hub 390
seen in FIG. 27 is disposed over the proximal end of the cement
cannula 200. Luer hub 390 has the same basic features as luer hub
240. Luer hub 390 is further formed so that the top most threading
392 that receives the luer fitting is formed to have a break 394.
This version of the invention includes a stylet cap 402, partially
seen in FIG. 28. Stylet cap 402 includes the same basic features of
stylet cap 260. Stylet cap 402 is further formed so that extending
inwardly from the inner surface of outer skirt 267 there is finger
404. In the illustrated version of the invention the longitudinal
axis of tab 255 and skirt finger 404 are coaxial. The side-to-side
width of finger 404 is less than the side-to-side width of tab
255.
[0125] As seen in FIG. 29, in this version of the invention, when
stylet cap 402 seats over luer hub 390, cap finger 404 seats in the
luer hub break 394. The finger-in-break engagement of the hub 390
and cap 402 prevents the stylet cap from rotating relative to the
luer hub. When the knob 140 is rotated to extend the blade 210,
cement cannula 200 only undergoes translation motion, the cannula
200 does not rotate. Again such rotation causes the knob notch 144
to rotate out of registration with cap tab 255. Owing to the
seating of the stylet cap finger 404 in fitting break 394, the
stylet cap 402 cannot be rotated to place the cap tab 255 in
registration with knob notch 144. As with the first described
version of the invention, since the cap tab 255 cannot be placed in
registration with the notch 144, removal of the stylet 230 from the
rest of the cavity creator is blocked.
[0126] In addition, alternate versions and geometries of the
described features of the present invention are possible. Thus,
alternate versions of cavity creator 100 may vary from what has
been illustrated. For example, in the described version of the
present invention, blade 210 has been shown as having a
substantially rectangular cross-sectional shape. In alternate
embodiments of the invention, blade 210 may be triangular, hooked,
or have almost any other shape depending on the specific size and
shape of the cavity to be created. In addition, head 212 has been
shown as having four facets to form a generally pyramid shape. In
still other embodiments of the present invention, head 212 can have
any alternate shape that still allows cavity creator 100 to be
inserted into the bone in which the cavity is to be formed. As a
further example, handle 110 can have any shape that provides the
practitioner the ability to grasp cavity creator 100. As still
another example, access cannula 160 and tip 170 can be formed as
one integrated element.
[0127] In some embodiments of the invention, the slots 224 in which
blade pins 278 do not extend completely through tip 170. In these
versions of the invention, the slots stop short of the outer
circumferential wall of pin 170. Adjacent each slot there is a
small web. One side of the web defines a portion of the outer
circumferential surface of the tip 170; the opposed surface defines
the end of the associated slot. In these versions of the invention,
the webs add strength to the tip when it is inserted into tissue or
the cavity creator 100 is rotated.
[0128] Likewise, cavity creator 100 of this invention may be used
with cement or filler delivery devices other than the disclosed
cartridge 40. For example in some versions of the invention, once
the cavity creator is in place, a tube shaped cartridge may be
disposed in the access cannula lumen. This cartridge is preloaded
with cement or filler. Once this cartridge is in place, a plunger
drives the cement from the cartridge into tip bore 214 and
discharge ports 266 and 166.
[0129] From the above it should also be clear that bone filler
other than cement may be supplied to the cavity created using the
assembly of this invention. Other potential bone fillers than
cement include: bone graft material or bone growth material.
Likewise, the fillers that can be delivered using this invention
are not limited to liquids and semi-solids. Solid implants like
beads or other rigid fillers may be added using the assembly of
this invention.
[0130] Similarly, other assemblies may be used to extend and
retract the blade 210. For example in some versions of the
invention, instead of using a threaded assembly to extend/retract
the cement cannula 200 relative to the access cannula 160 a tab may
be attached to the access cannula. In this version of the
invention, the practitioner slides the tab to cause displacement of
the access cannula in order to cause the desired
extension/retraction of the blade. For example, an elongated rod
may be slidably mounted to the access cannula 160. A rack of gear
teeth engage complementary teeth associated with the blade. The rod
is extended/retracted in order to cause a similar displacement of
the blade 210. An advantage of this version of the invention is
that the need to provide a moveable cement cannula is eliminated.
Alternatively a cable with ends that are extended or retracted may
be used to extend/retract the blade 210.
[0131] It should similarly be appreciated that other mechanisms may
be employed to prevent removal of the stylet when the blade is in
the extended state. For example the cement cannula may be provided
with a finger that is biased to press into a notch in the stylet
when the cement cannula is displaced in the forward direction. The
seating of the finger in the notch blocks removal of the stylet.
When the cement cannula is retracted proximally, the finger
retracts from the stylet to allow removal of the stylet.
[0132] Likewise, in some versions of the invention, the access
cannula may not have a lumen. In these versions of the invention,
it should be appreciated that once the cavity is created this
invention is removed and a separate delivery cannula is used as the
member for introducing filler material into the created cavity.
[0133] Furthermore, it should be understood that the materials and
the method from which the various components of cavity creator 100
are formed should not limit the scope of this invention. Thus, it
is intended that the appended claims not be limited to the details
shown and described herein, but rather cover all such variations
and modifications that come within the true spirit and scope of
this invention.
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